Eye tracking systems are used in various systems to implement various functions. Some examples of the functions that eye tracking systems implement include touch-free control of a cursor on a display, control of an apparatus in an aircraft cockpit or other vehicle, diagnostics and monitoring, and training/system simulation. A typical eye tracking system may include a suitable light source and a camera. The light source illuminates the face of a user, and the camera detects two reflections from one of the user's eye. The first reflection is from the front surface of the cornea. The second reflection is from the retina, and it illuminates the iris of the eye. Processing circuitry, using relatively straightforward geometrical calculations based on these two reflections, computes the direction in which the eye is gazing.
Conventional eye tracking systems may be generally categorized as desktop systems and wearable systems. Desktop systems rest on a surface and track the eye movement of a user that is facing the system, whereas wearable systems may be mounted on a pair of glasses and worn by the user. Both categories of presently known eye tracking systems do suffer certain drawbacks. For example, desktop systems typically have a relatively small depth of field and field of view. Moreover, many desktop systems may be inordinately large, may prevent portability, and may rely on a limited range of head motion. Wearable systems can be relatively clumsy and bulky, and may lack sufficient ruggedness. Furthermore, both system categories presently implement extensive computation for image analysis of the face and eye, both may work poorly in bright indoor or outdoor lighting, both may implement extensive computation to determine the gaze direction.
Hence, there is a need for an eye tracking system that is both wearable and overcomes at least the above-note shortcomings of presently known eye tracking systems. The present invention addresses at least this need.